Determining a level on a particular signal line is important in a wide variety of signal processing applications. These applications may include a wide variety of sensors such as temperature sensors, light sensors, decibel meters, power meters, etc. Demand for low-cost high-performance sensors which may be utilized in conjunction with complex Very Large Scale Integrated (VLSI) circuits is, in the main, being driven by the market growth of portable systems. Important applications of these types of sensors include: 1) power management in VLSI chips such as CPUs; 2) thermal system compensation for VLSI chips with embedded sensors; 3) temperature control of systems in which a VLSI chip is contained or with which a VLSI chip is utilized; 4) light or sound meters within digital recording devices such as cameras or the like; 5) sensitive touch sensors for use with input devices; etc.
In most cases, the determination of a desired signal level is accomplished by determining a ratio between the signal line for which the level is desired and one or more other signals line. Typically, this requires knowing the value of another signal lines to which the desired signal is being compared and determining the level of the unknown signal with respect to the known value of the other signal. This methodology is problematic for a number of reasons.
To begin with, to obtain an accurate result the value of the known signal need to be held constant, which may entail supporting circuitry including, for example, circuitry to achieve low impedance of the known signal. Additionally, even once the level of the desired signal is determined, to obtain a directly useful result this value must usually be scaled and calibrated which may entail an added degree of hardware of software complexity.
What is desired then are simple and robust methods, systems and apparatuses for determining the level of an input signal line, which allows any results to be easily scaled or calibrated.